SYSTEM AND METHOD FOR CALIBRATING BLUETOOTH LOW ENERGY SIGNAL STRENGTHS

• US 20160020861A1
• Filed: 07/16/2014
• Published: 01/21/2016
• Est. Priority Date: 07/16/2014
• Status: Active Grant

• Current Assignee: R2 Solutions LLC (Acacia Research Corporation)
• Original Assignee: Yahoo! Inc. (Apollo Global Management, Inc.)
• Inventors: Holz, Christian, Jin, Haojian
• Granted Patent: US 9,385,821 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 11/14 using ultrasonic, sonic, or infrasonic waves
• CPC Class Codes: G01S 5/02521 using a radio-map
• CPC Class Codes: G01S 5/26 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/28 takes precedence
• CPC Class Codes: G01V 1/3835 measuring position, e.g. by GPS or acoustically
• CPC Class Codes: G06Q 30/0261 based on user location
• CPC Class Codes: H04B 17/11 for calibration
• CPC Class Codes: H04W 4/023 using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds
• CPC Class Codes: H04W 4/025 using location based information parameters
• CPC Class Codes: H04W 4/80 Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication
• CPC Class Codes: H04W 52/0229 where the received signal is a wanted signal
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Disclosed is a system and method for calibrating BLE signal strengths to high-accuracy/precise distances. The present disclosure involves auto-calibrating BLE-based tracking systems, such as, for example, those used indoors using acoustic signals. The present disclosure enables BLE-based distance estimation to be accurate to decimeters and centimeters. The disclosed systems and methods utilize signals communicated to and from roaming devices in order to determine the distance(s) between the roaming device and installed BLE units. A signal-strength to distance map can then be constructed for reuse on any device with a Bluetooth component.

Claims

1. A method comprising steps of:

connecting, via a computing device, to a first Bluetooth Low Energy (BLE) unit at a location, said connection comprising identifying a beacon emitted from said first BLE unit and an identifier of the first BLE unit;

determining, via the computing device, a signal strength associated with the first BLE unit from said beacon;

emitting, via the computing device, a first signal, said first signal having a first timestamp associated with said emission and a second timestamp associated with reception by said first BLE unit;

receiving, at the computing device, second signal emitted from the first BLE unit, said second signal having a third timestamp associated with the emission from the first BLE unit and a fourth timestamp associated with said reception of the second signal;

determining, via the computing device, a distance between the computing device and the first BLE unit, said distance based upon an aggregated distance based on the first, second, third and fourth timestamps; and

storing, via the computing device, said distance in a storage, said distance stored in association with said signal strength and the identifier of the first BLE unit.

2. The method of claim 1, wherein said distance determination further comprises:

calculating the aggregated distance by determining a first time delay between the first timestamp and the second timestamp and a second time delay between the third timestamp and fourth timestamp, said aggregated distance equaling an aggregation of the first and second time delay;

multiplying the aggregated distance by the speed of sound in a current condition at said location; and

dividing the multiplied distance by 2, wherein a result of said division equals said distance.

3. The method of claim 2, wherein said speed of sound equals:

(331.3+0.606*v) m/s, wherein v is said current condition representing a current temperature at said location.

4. The method of claim 1, further comprising:

determining whether other BLE units are present at said location; and

when other BLE units are present, repeating said steps for all other BLE units.

5. The method of claim 1, wherein said second timestamp and said third timestamp are recorded by the first BLE unit, wherein said computing device receives said second timestamp and said third timestamp in a communication from the first BLE unit.

6. The method of claim 1, wherein said aggregated distance represents a first distance from a speaker of the computing device to a microphone of the first BLE unit, and a second distance from a speaker of the first BLE unit to a microphone of the computing device.

7. The method of claim 1, wherein said computing device is a mobile device.

8. The method of claim 1, further comprising:

determining a position of said computing device based on said distance;

searching an advertisement database for an advertisement based on said position, said advertisement associated with an entity at said location, said entity associated with the first BLE unit; and

selecting said advertisement, wherein said advertisement is to be displayed on a display of said computing device.

9. A method comprising steps of:

connecting, via a computing device, to a first Bluetooth Low Energy (BLE) unit at a location, said connection comprising identifying an identifier of the first BLE unit;

transmitting, via the computing device, a command for said first BLE unit to emit a signal, said signal being an acoustic signal, said command associated with a first timestamp;

receiving, at the computing device, said signal from the first BLE unit, said reception associated with a second timestamp;

determining, via the computing device, a time delay between said first timestamp and said second timestamp;

determining, via the computing device, a distance between the computing device and the first BLE unit, said distance determination comprising multiplying said time delay by the speed of sound in a current temperature at said location; and

storing, via the computing device, said distance in a storage, said distance stored in association with the identifier of the first BLE unit.

10. The method of claim 9, further comprising:

determining whether other BLE units are present at said location; and

when other BLE units are present, repeating said steps for all other BLE units.

11. The method of claim 9, wherein said connection is a Bluetooth connection.

12. A method comprising steps of:

connecting, via a computing device, to a first Bluetooth Low Energy (BLE) unit at a location, said connection comprising identifying an identifier of the first BLE unit, wherein said BLE unit records and processes transmitted audio signals;

transmitting, via the computing device, a first audio signal, said first audio signal associated with a first timestamp;

receiving, via the computing device, a response from said first BLE unit, said response associated with a second timestamp corresponding to said reception by the computing device, wherein said response is based upon the first BLE unit receiving the first audio signal and communicating said response back to said computing device;

determining, via the computing device, a time delay between the first timestamp and the second timestamp;

determining, via the computing device, a distance between the computing device and the first BLE unit, said distance determination comprising multiplying said time delay by the speed of sound in a current temperature at said location; and

storing, via the computing device, said distance in a storage, said distance stored in association with the identifier of the first BLE unit.

13. The method of claim 12, further comprising:

determining whether other BLE units are present at said location; and

when other BLE units are present, repeating said steps for all other BLE units.

14. The method of claim 12, wherein the first BLE unit records and processes audio signals based on a command from said computing device.

15. A method comprising:

connecting, via a computing device, to a first Bluetooth Low Energy (BLE) unit at a location, said connection comprising identifying a beacon emitted from said first BLE unit and an identifier of the first BLE unit;

determining, via the computing device, an observed signal strength associated with the first BLE unit from said beacon;

searching, via the computing device, a storage associated with said location based on the observed signal strength and the identifier of the first BLE unit, said storage storing, for each BLE unit at said location, a BLE identifier, signal strength and a measured distance;

determining, via the computing device, a distance between the computing device and the first BLE unit, said distance corresponding to a measured distance for the first BLE unit in said storage; and

receiving, at the computing device, said distance.

16. The method of claim 15, further comprising:

identifying the stored signal strength in the storage associated with the first BLE unit identifier; and

identifying the measured distance based on the stored signal strength.

17. The method of claim 15, further comprising:

determining, based on said searching, that the storage contains no entry for the measured signal strength associated with the first BLE unit identifier and observed signal strength;

identifying a next smaller and next larger signal strength in the storage from that of the observed signal strength for the first BLE unit; and

calculating a distance based on the identified next smaller and next larger signal strengths through linear interpolation.

18. A non-transitory computer-readable storage medium tangibly encoded with computer-executable instructions, that when executed by a processor associated with a computing device, performs a method comprising:

connecting to a first Bluetooth Low Energy (BLE) unit at a location, said connection comprising identifying a beacon emitted from said first BLE unit and an identifier of the first BLE unit;

determining a signal strength associated with the first BLE unit from said beacon;

emitting a first signal, said first signal having a first timestamp associated with said emission and a second timestamp associated with reception by said first BLE unit;

receiving second signal emitted from the first BLE unit, said second signal having a third timestamp associated with the emission from the first BLE unit and a fourth timestamp associated with said reception of the second signal;

determining a distance between the computing device and the first BLE unit, said distance based upon an aggregated distance based on the first, second, third and fourth timestamps; and

storing said distance in a storage, said distance stored in association with said signal strength and the identifier of the first BLE unit.

19. The non-transitory computer-readable storage medium of claim 18, wherein said distance determination further comprises:

calculating the aggregated distance by determining a first time delay between the first timestamp and the second timestamp and a second time delay between the third timestamp and fourth timestamp, said aggregated distance equaling an aggregation of first and second time delay;

multiplying the aggregated distance by the speed of sound in a current condition at said location; and

dividing the multiplied distance by 2, wherein a result of said division equals said distance.

20. A system comprising:

a computing device comprising;

memory storing computer-executable instructions; and

one or more processors for executing said computer-executable instructions for;

connecting to a first Bluetooth Low Energy (BLE) unit at a location, said connection comprising identifying a beacon emitted from said first BLE unit and an identifier of the first BLE unit;

determining a signal strength associated with the first BLE unit from said beacon;

emitting a first signal, said first signal having a first timestamp associated with said emission and a second timestamp associated with reception by said first BLE unit;

receiving second signal emitted from the first BLE unit, said second signal having a third timestamp associated with the emission from the first BLE unit and a fourth timestamp associated with said reception of the second signal;

determining a distance between the computing device and the first BLE unit, said distance based upon an aggregated distance based on the first, second, third and fourth timestamps; and

storing said distance in a storage, said distance stored in association with said signal strength and the identifier of the first BLE unit.